Representing the 1st addition to my metal card collection, I'm looking forward to collecting more of these "coin-like" baseball cards.

From '84-'91, one set of 12 metal cards was issued each year in either aluminum, bronze, or silver.
From '83-'91, one different bronze card was issued each year
From '84-'91, one different pewter card was issued each year
In 1995, one different bronze card was issued each month.

To my knowledge, there were total of: 12x8 + 9 + 8 + 12 = 125 different metal cards issued between 1983-1995. This estimate doesn't count the different metal types; just the different card types.